The home secretary, Theresa May, has been asked to answer 14 outstanding questions about the Brodie Clark affair put to her by the Commons home affairs committee before the ousted UK border force chief gives evidence next week.

Clark, 60, who has been legally advised not to make any further statements before he gives evidence on Tuesday, will be immediately followed by Rob Whiteman, the UK Border Agency's chief executive.

A statement by Whiteman alleged that Clark was suspended after admitting he had gone beyond ministerial instructions in secretly relaxing passport checks this summer at Britain's airports and ports.

May and the Home Office's permanent secretary, Helen Ghosh, both addressed a "steady the ship" open meeting on Thursday for staff at the department's Marsham Street headquarters designed to boost morale after a turbulent six days. It was said to be short and upbeat.

An interim report from one of the two internal UK Border Agency inquiries into the border checks row may be published as early as next week.

The full report by the independent inspector of immigration, John Vine, a former Tayside chief constable, into the affair will not be published until after Christmas.

Matthew Coats, who was the UKBA's head of immigration, has temporarily taken over Clark's role in charge of the border force. A notice on the UKBA's website says the border force operations manual, which sets out the rules for passport checks at the border, is "currently being updated".

The Labour party has written to Gus O'Donnell, the cabinet secretary, urging him under the civil service code to investigate whether Home Office special advisers were responsible for negative media briefings about Clark including allegations that he was a "rogue civil servant" who might face criminal charges for putting Britain's border security at risk

The home secretary told MPs this week that she would not be publishing any of the paper trail that led to the suspension and then resignation of the UK border force's head. He quit and lodged a constructive dismissal claim on Tuesday night, accusing May of blaming him for the border checks row for her 'political convenience'.

In addition to the 14 questions to the home secretary, Keith Vaz, chairman of the Commons home affairs committee, has also submitted a further seven questions to the permanent secretary.

The requests for further information centre on the leaked UKBA operational instructions to the home secretary centre on ministerial involvement in the drawing of the UKBA's operational instruction – issued on 28 July – setting out the checks that need no longer be undertaken as part of the pilot. The MPs are also keen to establish the exact nature and extent of the pilot scheme and for publication of the paperwork detailing communications between ministers and UKBA officials on the scheme.

"The committee is determined to get to the bottom of this serious breach of security," said Vaz. "The resignation statement of Mr Clark directly contradicts evidence given by the home secretary to the home affairs committee ... It also contradicts the statements made since last Thursday which quoted that Mr Clark was solely responsible for the unauthorised relaxation of border checks."

Clark in his resignation statement denied he had acted improperly and announced he was suing the home secretary for constructive dismissal.